Despite significant advancements in fluid dispensing devices and systems, many problems that have existed for decades related to such devices and systems remain unsolved. These problems exist in many different fluid dispensing applications, but have a particularly significant impact upon fluid dispensing devices and systems in the food and beverage industry as will be described below. Comestible fluid dispensers in this industry can be found for dispensing a wide variety of carbonated and non-carbonated pre-mixed and post-mixed drinks, including for example beer, soda, water, coffee, tea, and the like. Fluid dispensers in this industry are also commonly used for dispensing non-drink fluids such as condiments, food ingredients, etc. The term xe2x80x9ccomestible fluidxe2x80x9d as used herein and in the appended claims refers to any type of food or drink intended to be consumed and which is found in a flowable form.
A majority of the long-standing problems in the comestible fluid dispensing art are found in dispensing applications for carbonated beverages. First, because the fluid being poured is carbonated and is therefore sensitive to pressure drops, conventional carbonated comestible fluid dispensers are generally slow, requiring several seconds to fill even an average size cup or glass. Second, when flow speeds are increased, the dispensed beverage often has an undesirably large foam head (which can overflow, spill, or otherwise create a mess) and is often flat due to the fast dispense. Some existing devices use hydrostatic pressure to push comestible fluid out of a holding tank located above the dispensing nozzle. One such device is disclosed in U.S. Pat. No. 5,603,363 issued to Nelson. Unfortunately, these devices do not provide for pressure control at the nozzle, and (at least partly for this reason) are limited in their ability to prevent foaming and loss of carbonation in the case of carbonated comestible fluids. The working potential of rack pressure in such devices is largely wasted in favor of hydrostatic pressure. By not maintaining rack pressure to the nozzles in these devices, carbonated comestible fluid inevitably loses its carbonation over time while waiting for subsequent dispenses. Also, like other existing beer dispensers, such devices cool and/or keep the comestible fluid cool by the relatively inefficient practice of cooling a reservoir or supply of comestible fluid.
Another problem of conventional comestible fluid beverage dispensers is related to the temperature at which the fluid is kept prior to dispense and at which the fluid is served. Some beverages are typically served cold but without ice, and therefore must be cooled or refrigerated prior to dispense. This requirement presents significant design limitations upon dispensers for dispensing such beverages. By way of example only, beer is usually served cold and must therefore be refrigerated or cooled prior to dispense. Conventional practice is to cool the beer in a refrigerated and insulated storage area. The process of refrigerating a beer storage area sometimes for an indefinite period of time prior to beer dispense is fairly inefficient and expensive. Such refrigeration also does not provide for quick temperature control or temperature change of the comestible fluid to be dispensed. Specifically, because the comestible fluid in storage is typically found in relatively large quantities, quick temperature change and adjustment by a user is not possible. Also, conventional refrigeration systems are not well suited for responsive control of comestible fluid temperature by automatic or manual control of the refrigeration system.
Unlike numerous other comestible fluids which do not necessarily need to be cooled (e.g., soft drinks, tea, lemonade, etc., which can be mixed with ice in a vessel after dispense) or at least do not require a cooling device or system for fluid lines running between a refrigerated fluid source and a nozzle, tap, or dispensing gun, beer is ideally kept cool up to the point of dispense. Therefore, many conventional dispensers are not suitable for dispensing beer. For example, beer located within fluid lines between a refrigerated fluid source and a nozzle, tap, or dispensing gun can become warm between dispenses. Warm beer in such fluid lines must be served warm, be mixed with cold beer following the warm beer in the fluid lines, or be flushed and discarded. These options are unacceptable as they call either for product waste or for serving product in a state that is less than desirable. In addition, because many comestible fluids are relatively quickly perishable, holding such fluids uncooled (such as in fluid lines running from a refrigerated fluid source to a nozzle, tap, or dispensing gun) for a length of time can cause the fluid to spoil, even fouling part or all of the dispensing system and requiring system flushing and cleaning.
Because many comestible fluids should be kept cool up to the point of dispense, the apparatus or elements necessary to achieve such cooling have significantly restricted conventional dispenser designs. Therefore, dispensers for highly perishable fluids such as beer are therefore typically non-movable taps connected via insulated or refrigerated lines to a refrigerated fluid source, while dispensers for less perishable fluids (and especially those that can be cooled by ice after dispense) can be hand-held and movable, connected to a source of refrigerated or non-refrigerated fluid by an unrefrigerated and uninsulated fluid line if desired.
A comestible fluid dispenser design issue related to the above problems is the ability to clean and sterilize the dispenser as needed. Like the problems described above, improperly cleaned dispenser systems can affect comestible fluid taste and smell and can even cause fresh comestible fluid to turn bad. Many potential dispenser system designs cannot be used due to the inability to properly clean and sterilize one or more internal areas of the dispenser system. Particularly where dispenser system designs call for the use of small components or for components having internal areas that are small, difficult to access, or cannot readily be cleaned by flushing, the advantages such designs could offer are compromised by cleaning issues.
The problems described above all have a significant impact upon dispensed comestible fluid quality and taste, but also have an impact upon an important issue in most dispenser applications: speed. Whether due to the inability to use well known devices for increasing fluid flow, due to the fact that carbonated fluids demand particular care in their manner of dispense, or due to dispenser design restrictions resulting from perishable fluids, conventional comestible fluid dispensers are invariably slow and inefficient.
In light of the problems and limitations of the prior art described above, a need exists for a comestible fluid dispensing apparatus and method capable of rapidly dispensing comestible fluid in a controlled manner without foaming or de-carbonating the fluid even between extended periods between dispenses, which is capable of maintaining the comestible fluid throughout the dispensing apparatus cool indefinitely and with high efficiency, which permits quick and accurate temperature control of comestible fluid dispensed by automatic or manual refrigeration system control, which can be in the form of a mounted or hand-held apparatus, which can be easily cleaned and sterilized even though relatively small and difficult to access internal areas exist in the apparatus, and which is capable of monitoring apparatus operation and dispense parameters for controlling dispense pressure, flow speed, and head size. Each preferred embodiment of the present invention achieves one or more of these results.
The present invention addresses the problems of the prior art described above by providing a nozzle assembly capable of controlling pressure of comestible fluid exiting the nozzle assembly, a refrigeration system that employs refrigerant pressure control in the refrigeration system to provide efficient and superior control of comestible fluid temperature, heat exchangers of a type and connected in a manner to cool comestible fluid up to the exit ports of dispensing nozzles, a sterilization system for effectively sterilizing even hard to access locations outside and inside the comestible fluid dispensing system, and a hand held comestible fluid dispenser capable of cooling and selectively dispensing one of several warm comestible fluids supplied thereto.
The present invention solves the problem of how to employ comestible fluid rack pressure as a pressure for the entire dispensing system without the associated dispense problems such relatively high pressure can produce (particularly in carbonated beverage systems such as beer dispensing systems, where it is most desirable to keep carbonated fluid pressurized for an indefinite period of time between dispenses). In one embodiment of the present invention, nozzle assemblies from which comestible fluid is dispensed are provided with valves each having an open position and a range of closed positions corresponding to different comestible fluid pressures at the dispensing outlet of the nozzle. Control of the valve to enlarge a fluid holding chamber or reservoir in the nozzle assembly prior to opening results in a lower controllable dispense pressure. Preferably, the valve is a plunger valve in telescoping relationship with a housing of the nozzle. Alternative embodiments of the present invention employ other pressure reduction elements and devices to control dispense pressure at the nozzle. For example, a purge line can extend from the nozzle assembly or from the fluid line supplying comestible fluid to the nozzle assembly. By bleeding an amount of comestible fluid from the nozzle or from the fluid line prior to opening the nozzle, a system controller can reduce comestible fluid pressure in the nozzle to a desired and controllable dispense level. Other embodiments of the present invention control comestible fluid pressure at the nozzle by employing movable fluid line walls, deformable fluid chamber walls, etc. Flow information can be measured and monitored by the control system via the same pressure sensors and/or flowmeters used to control nozzle valve actuation, thereby permitting a user to monitor comestible fluid dispense and waste, if desired.
Some preferred embodiments of the present invention employ a diffuser in the nozzle to reduce velocity of fluid dispensed therefrom. Specifically, the internal cross sectional area of the diffuser increases toward the dispensing outlet of the nozzle, thereby reducing fluid velocity toward the dispensing outlet and resulting in more controllable fluid flow. Also preferably, a section of the nozzle downstream of the diffuser and upstream of the dispensing outlet has a relatively constant cross sectional area for further improving fluid flow characteristics to and through the dispensing outlet.
In those embodiments where a diffuser is used to reduce velocity in the nozzle, the valve is preferably a plug-type valve having open and closed positions without a significant range of closed positions as described above with reference to the plunger-type valve (although such a plunger-type valve can be used with a nozzle diffuser if desired. Pressure-controlling elements and structure can also or instead be used in conjunction with the nozzle diffuser, if desired. The plug-type valve is preferably provided with a deformable gasket for generating a fluid-tight seal with the dispensing outlet when the valve is closed, and can have a sensor rod passed therethrough for triggering opening and/or closing of the valve.
In some preferred embodiments, fluid flows into the nozzle at an angle with respect to a longitudinal axis of the nozzle (and an internal chamber defined therein), thereby reducing undesirable forces upon the fluid entering the nozzle and reducing the likelihood of foaming especially in the case of carbonated fluids.
A priming and purging valve assembly can be used in any of the nozzle assemblies embodiments of the present invention for user-controlled or automatic priming and purging of the nozzle assembly and upstream system connected thereto. Specifically, one or more fluid sensors can be located at a relatively high point in the fluid line for detecting air or gas bubbles or pockets therein. The priming and purging valve assembly has a priming and purging valve connected to the fluid line and preferably has a check valve connected between the priming and purging valve and the fluid line for preventing backflow of ejected fluid into the fluid line. When an air or gas bubble is detected by the fluid sensor, the user can perform a purging or priming operation by opening the priming and purging valve (by a control or by manually operating the priming and purging valve). This valve can remain open for a set time, until the user closes the valve, or until the fluid sensor no longer detects air or gas in the fluid line. In some embodiments, the priming and purging valve assembly can even perform a priming or purging operation automatically under trigger control by the fluid sensor.
To improve temperature control and cooling efficiency of the dispensing system, the present invention preferably employs heat exchangers adjacent to the nozzle assemblies, with no substantial structural elements to block flow between each heat exchanger and its respective nozzle assembly. Highly efficient plate-type heat exchangers are preferably used for their relatively high efficiency and small size. A venting system or plug can be used to vent or fill any head space that may exist in the heat exchangers, thereby avoiding cleaning and pressurized dispensing problems. Due to their locations close to the nozzle assemblies, the heat exchangers generate convective recirculation through the nozzle assemblies to send cold comestible fluid to the terminal portion of the nozzle assembly and to receive warmer comestible fluid therefrom. Comestible fluid therefore remains cool up to the dispensing outlet of each nozzle assembly. Also, because the comestible fluid is cooled near the point of dispense, the inefficient practice of refrigerating the source of the comestible fluid for a potentially long time between dispenses by convective cooling in an insulated storage area can be eliminated in many applications.
The present invention can include one or more temperature sensors connected to the fluid line at any location between the fluid source and the nozzle dispensing outlet. When the temperature of the fluid in the fluid line rises above a pre-determined threshold temperature (e.g., for cold fluids) or falls below a pre-determined threshold temperature (e.g., for warm fluids), the temperature sensor can trigger the priming and purging valve assembly described above to open, thereby purging and moving sufficient fluid through the system""s heat exchanger to cool or heat the fluid below or above a pre-determined threshold level, respectively. Purging the system in this manner to control temperature with a temperature sensor can be done manually or automatically in much the same manner as described above with reference to the fluid sensor.
The present invention can take the form of a dispensing gun if desired, thereby providing for dispensing nozzle mobility and dispense speed. Preferred embodiments of the dispensing gun have a heat exchanger located adjacent to a nozzle assembly to generate cooling convective recirculation in the nozzle assembly as discussed above. To increase portability and a user""s ability to manipulate the dispensing gun, the heat exchanger is a highly efficient heat exchanger such as a plate-type heat exchanger. The dispensing gun can have multiple comestible fluid input lines, thereby permitting a user to selectively dispense any of the multiple comestible fluids. Preferably, a valve is located between the heat exchanger and the nozzle assembly of the dispensing gun and can be controlled by a user via controls on the dispensing gun to dispense any of the fluids supplied thereto. Like the nozzle assemblies and heat exchangers mentioned above, the location of a heat exchanger near the point of dispense removes the requirement of refrigerating the comestible fluid supply in many applications. Also, pressure control at the nozzle is preferably provided by a nozzle assembly valve having a range of closed positions as mentioned above.
To further improve control of comestible fluid temperature, the present invention preferably has a refrigeration system that is controllable by controlling refrigerant temperature and/or pressure. Specifically, an evaporator pressure regulator can be used to control refrigerant pressure upstream of the compressor in the refrigeration system, thereby controlling the cooling ability of refrigerant in the heat exchanger and controlling the temperature of the refrigerant passing through the heat exchanger. In addition or alternatively, a hot gas bypass valve can bleed hot refrigerant from the compressor for reintroduction into cold refrigerant upstream of the heat exchanger, thereby also controlling the cooling ability of refrigerant in the heat exchanger and controlling the temperature of comestible fluid passing through the heat exchanger, particularly in the event of a low or zero-load operational condition in the refrigeration system (e.g., between infrequent dispenses when fluid in the heat exchanger is already cold).
Preferred embodiments of the present invention have an ultraviolet light assembly for sterilizing external and internal surfaces of the system. The ultraviolet light assembly has an ultraviolet light generator and has one or more ultraviolet light transmitters for transmitting the ultraviolet light to various locations in and on the dispensing system. For example, ultraviolet light can be transmitted to the nozzle exterior surfaces frequently immersed in sub-surface filling operations, head spaces in the heat exchangers, and even to locations within fluid lines of the dispensing system. The ultraviolet light transmitters can be fiber optic lines, light pipes, or other conventional (and preferably flexible) members capable of transmitting the ultraviolet light a distance from the ultraviolet light generator to the locations to be sterilized.
Further objects and advantages of the present invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the drawings.